1. Field of the Invention
The present invention relates to a curable organopolysiloxane composition, a method of producing such a composition, a cured product thereof, the use of such a cured product as a heat conductive layer, a semiconductor device containing such a heat conductive layer, and a method of producing such a semiconductor device.
2. Description of the Prior Art
Heat generating electronic components mounted on printed wiring boards, including IC packages such as CPUs, undergo an increase in temperature as a result of the heat generated during operation of the component, and because this temperature increase can cause deterioration in the component performance or even failure of the component, a heat conductive sheet with good thermal conductivity or a heat conductive grease is usually sandwiched between the IC package and a heat radiating member with heat radiating fins, thereby efficiently conducting the heat generated by the IC package or the like through to the heat radiating member, which then radiates the heat away. However, as the performance of electronic components and the like improves, the heating value of the components also tends to increase, meaning there is a demand for the development of materials and members with even better thermal conductivity than conventional materials.
Conventional heat conductive sheets offer workability advantages as they are easily mounted and installed. Furthermore, heat conductive greases offer other advantages in that they are unaffected by irregularities in the surfaces of the CPU or the heat radiating member, and conform to, and follow these irregularities, meaning the two components can be held together without any intervening gaps, thus ensuring a small interface thermal resistance. However, heat conductive sheets and heat conductive greases both require the addition of a heat conductive filler in order to achieve thermal conductivity, and because the apparent viscosity of either material must be restricted to a certain upper limit, in order to prevent any obstacles to workability or processability within the production process in the case of a heat conductive sheet, and in order to prevent any workability problems during application by syringe to a heat generating component in the case of a heat conductive grease, there is a limit to how much heat conductive filler can be added to either material, meaning a favorable thermal conductivity effect cannot be achieved.
As a result, methods of blending a low melting point metal into a heat conductive paste (patent reference 1, patent reference 2), and a particle-based material that fixes and stabilizes a liquid metal within a three phase complex (patent reference 3) have been proposed. However, these heat conductive materials that use low melting point metals have a number of drawbacks including contamination of components other than the coated component, and bleeding of oily material if used for extended periods.
[Patent Reference 1]
JP7-207160A
[Patent Reference 2]
EP 0696630
[Patent Reference 3]
U.S. Pat. No. 6,624,224